1. Field of the Invention
This invention relates to electric lamps and has particular reference to an improved fluorescent lamp unit that is adapted for use in low temperature environments.
2. Description of the Prior Art.
Fluorescent lighting assemblies having integral enclosures or jackets that physically protect and thermally insulate the fragile lamp envelope are well known in the art. A lighting unit of this type having a tubular jacket or shield of rigid plastic that is held in spaced-apart enclosing relationship with the lamp envelope by a pair of resilient annular support members that are slipped over the ends of the lamp and effect a force fit with the adjacent ends of the shield is disclosed in U.S. Pat. No. 3,124,307 issued Mar. 10, 1964 to T. E. Hoskins et al. In a more recent design, a rigid open-ended plastic sleeve is held in enclosing and insulating relationship with the glass envelope of a fluorescent lamp by slipping the sleeve over a pair of rubber grommets that are placed on and compressively grip the ends of the envelope. A fluorescent lamp unit constructed in this fashion is disclosed in U.S. Pat. No. 3,720,826 issued Mar. 13, 1973 to J. F. Gilmore et al.
A fluorescent lamp having an insulating tubular jacket composed of rigid oriented plastic material that is secured to the lamp by shrinking the ends of the tubular jacket so that they grip the lamp, or which is made of glass and is held in place by a pair of overlapping shrunk plastic sleeves, is described in U.S. Pat. No. 3,602,759 issued Aug. 31, 1971 to G. S. Evans.
While the tubular shield and jacket assemblies of the prior art protected the glass envelopes of the fluorescent lamps from accidental breakage and the detrimental effects of cold ambient temperatures, they are rather expensive and create production problems since they require specially-molded supporting components or gaskets and several time-consuming operations to force-fit the various components together in operative relationship with the lamp.